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Drinking Water Generally Safe, but San Francisco Sometimes Has High Levels of TTHMs
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Under the Safe Drinking Water Act Amendments of 1996, water agencies are required to report to customers on the quality of their drinking water. Even within legal limits set by the federal government, some contaminants in tap water can pose potential health risks, especially to pregnant women, certain infants, some frail elderly people, and people with weakened immune systems such as those living with AIDS, undergoing chemotherapy, or recovering from organ transplants.

On occasion in 1999 and 2000, TTHMs, byproducts of chlorination that are suspected of causing cancer and have been linked to miscarriages, were present in San Francisco tap water at levels above the legal limit. The federal limit is now 100 parts per billion, but will drop to 80 parts per billion in January 2002. This lower standard could put several Bay Area utilities above the legal limit.

Studies have shown that pregnant women exposed to water with levels of TTHMs of 75 parts per billion during their first trimester may have higher risks of miscarriage and of delivering babies with birth defects. In addition, according to the East Bay Municipal Utility District, some people who drink water containing TTHMs above the legal limit over many years may experience liver, kidney, or central nervous system problems, and may have an increased risk of cancer.

TTHMs are produced when surface water sources that contain organic material are treated with chlorine. Agencies like the San Francisco Water Department and the East Bay Municipal Utility District could markedly reduce TTHMs in their water by filtering it (San Francisco doesn't filter at all), switching to safer, equally effective disinfectants, or both. Contra Costa, which has the best record on TTHMs, both filters and uses ozone to treat surface water.

Making the Risks Public
It's not only water quality that must be improved. Public access to information on water contaminants needs improvement as well. While the six Bay Area water agencies' right-to-know reports examined by NRDC researchers contained the legally required information on water contaminants, many also made broad, misleading claims, such as, "Your water is of the highest quality." Other reports presented data in a confusing way: by providing averages for contaminants like MtBE and TTHMs, the agencies showed contaminant levels that were under the legal limits, even though the levels may have spiked above those limits several times during the year.

To clearly convey information to consumers about safety risks in drinking water, the yearly consumer confidence reports should provide information on: the source of the water; which contaminants have been detected and their origin; any violation of federal or state drinking water standards; and the health risks posed by the contaminants found in tap water (although water utilities are only required to provide information on health risks of the specific contaminants that have been detected in the water).

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